1. Field of the Invention
The invention relates to the technology of making optical DWDM (Dense-Wavelength-Division-Multiplexing) multiplexor or demultiplexor, and particularly to the DWDM multiplexor or demultiplexor with a built-in V-groove dual fiber collimator.
2. The Related Art
The future communication networks demand ever increasing bandwidth. Transmitting several channels in a single optical fiber at different wavelength, DWDM can dramatically enhance the transmission capacity of the optical fiber communication system. The device that combines different wavelength channels into one fiber is a multiplexor, and the device that divides the multiplexed channels into individual ones is a demultiplexor. A variety of technologies has been exploited to develop high performance DWDM multiplexor/demultiplexor, including fiber Bragg grating, optical integrated circuit, fused fiber MachZander interferometer, dichoric coating technology, etc. An International standard wavelength grid has been suggested by the ITU (International Telecommunication Union) for defining the center wavelengths of the DWDM channels.
The traditional way uses a Y-branch structure of three conventional fiber optic collimators wherein the incident angle on the DWDM filter is tuned by changing/adjusting the angles between the collimators, whereby the center wavelength of such a multiplexor/demultiplexor can coincide with the desired ITU wavelength. The disadvantage of this traditional way is mainly with difficulties to reduce the overall size to achieve a robust and compact structure. The related references include U.S. Pat. Nos. 4,464,022, 5,204,771, 5,574,596, 5,629,995, 5,712,717, 5,748,350, 5,764,825, 5,786,915, 5,799,121 and 5,808,763.
Therefore, the invention is to provide a multi-port fiber optic device such as a DWDM multiplexor/demultiplexor, by using at least one dual-fiber collimator therein, for achieving a compact and robust structure, lower cost, flexibility in manufacturing, and high stability in hazardous environment.
According to an aspect of the invention, a multi-port fiber optic device includes a dual fiber first collimator which comprises two in-and-out optical fibers, arranged in a parallel spatial relation in a chip with a pair of parallel V-shaped grooves therein wherein the distance between such pair of V-shaped grooves is predetermined for compliance with the required incidence angle onto the DWDM filter. A lens is positioned in front of the ends of both the optical fibers. A filter is attached to the front surface of the lens opposite to the pair of optical fibers, which decides the in-pass-band and the out-pass-band of the light wherein the in-pass-band light will penetrate the filter while the out-pass-band light will be reflected to the output optical fiber. A second collimator confronts the first collimator with at least one output optical fiber which transmit the light pass through the filter from the first collimator. A soldering sleeve coaxially enclose both the first and second collimators to finalize the whole package of the multi-port fiber optic device.